1. Field of the Invention
The invention lies in the field of conveying and processing technology of flat products, in particular printed products, and relates to a method and to a device for creating a cycled product stream of product units in a predefined sequence.
2. Description of Related Art
The creation of a product stream, also called conveying stream, from flat product units in a predefined sequence or succession in particular serves for the purpose of the further processing in this predefined sequence. A predefined sequence according to definition represents a sorted succession of product units.
A preferred application lies in mailroom technology on composing and, as the case may be, addressing product units in a predefined sequence according to a predefined sequence of addresses, which for example corresponds to a mailing route. The mailing route represents the route that the deliverer goes on or travels when delivering the product units.
In mailroom technology, different products must be sorted according to addressees, composed and aggregated into groups, the so-called product units. Such product units can, e.g., be present as small stacks or as collections. The product units as a result can be product compositions. The background to this is the fact that as a rule, each addressee receives an individual composition of different products, wherein the different products of a product unit can be personalised, e.g. addressed.
The products of a product unit can be present in the form of letters or addressed printed products such as magazines, newspapers or advertising supplements. Moreover, individual or all products, such as e.g. letters, journals, cards or booklets of a product unit that are envisaged for a certain addressee can also be individualised with the address concerned before or during the composition of a product unit.
Moreover, the product unit can also comprise products that are not addressed, but are matched to the personal preferences of the addressee. These can be newspapers, magazines or advertising supplements.
The addressees as a rule are sought by the deliverer in a predefined sequence, which, e.g., corresponds to the mailing route. For this reason, it is important for the product units to also be made available for delivery in the sequence of the delivery or mailing route.
Therefore, there exits the need for the complete product stream of product units, also called product stream, to be created in the predefined sequence already on producing the production units. This sequence should also be retained with subsequent further processing steps and conveying steps.
A further processing can be the addressing of all or of selected products or the addressing of an envelope, which aggregates the product unit. Moreover, the further processing can also include packaging of the product units, e.g. into an envelope or into a protective covering of plastic.
The addresses, for example, are printed onto the product units in accordance with the sequence, in a printer that is arranged downstream of the sequence creation in the conveying direction. The products can subsequently likewise be conveyed in accordance with the sequence according to a predefined mailing or delivery route (sequence of the recipients) to a delivery device, from which the product units are delivered.
The above embodiments are to be considered as part of the disclosure of the invention.
It can occur that a product unit contrary to the setting or instructions is not formed or only in a faulty manner. Thus, for example, products that were not delivered for various reasons can be absent in a faulty product unit. Moreover, it can also be the case that the product unit comprises damage products.
A missing or faulty product unit must be corrected at a later stage (belatedly) or be created afresh, before this can be provided for the dispatch or for the further processing. A correction of the product unit, amongst other things, means that the product unit is completed by way of feeding the missing products, that the faulty products are exchanged or that excess products are discharged.
The creation or completion of the missing or faulty product unit at a later stage, however, leads to the fact that this is no longer at the correct place in the sequence, which has been created in the meantime, and which is conveyed further in the device.
Since one wishes to retain the predefined succession of the sequence of product units under all circumstances, the further conveying of the product units of the sequence that are correctly composed straightaway must be stopped in the device and the continuous creation of product units must be interrupted, for the belated creation or completion of the one product unit.
The belatedly correctly created product unit is then introduced into the sequence at the correct location. The further conveying of the sequence and, thus, the creation of further subsequent product units can be resumed again.
As an alternative to this method, the sequence section concerned can also be led into a waiting loop and be fed to the further conveying again only after completion by the mentioned product unit. Here too, however, the creation of subsequent product units is interrupted until the sequence section concerned is completed and can be conveyed further.
Thus EP 2 107 023 A1 describes a method and a device for completing a sequence of product units given an occurrence of faulty product units. The solution to the problem which is disclosed in this publication document is based on leading back the product sequence along a closed circulating path to the grouping stretch, at which the product units were composed, and on completing the faulty product unit. The completed sequence is subsequently fed to a transfer device for the transfer to a conveying-away unit.
Although a transfer of a predefined sequence to a conveying-away device is ensured with this method, the manufacturing of subsequent product units subsequently to the faulty product unit must, however, be interrupted until the faulty product unit has again been led through the grouping stretch and completed.
The procedure described above therefore leads to many production interruptions. The performance or efficiency of the device is significantly reduced. The device in the most unfavourable case does not achieve the required throughput of product units per time unit.
U.S. Pat. No. 5,171,005 also describes a device and a method for composing newspapers. The device includes a plurality of feed stations and a delivery station, wherein in each case a filling shaft for receiving printed products as a stack is assigned to the feed stations. Receiving compartments that are arranged on a circular rotating device are led along a closed circular path past the feed stations that are arranged circularly and sequentially along this circular path, as well as past the delivery station. The receiving compartments that are led past the feed stations are charged with newspaper parts from the associated filling shafts. The composed newspapers at the delivery station are delivered from the receiving compartments that run past, to a gripper conveyor.
In the case of a feed error, the rotation device undergoes an additional revolution, in order to lead the receiving compartment affected by the feed error back to the corresponding feed station and to correct the feed error. A sequence of different newspaper products, which is predefined for the later dispatch, can be retained in this manner.
Here too, the production of subsequent product units must be interrupted until the sequence, which is led in the rotation device, is completed and can be fed to a conveying-away device.
EP-A 0 511 159 moreover describes a method as well as a corresponding device that serves for composing complex product units by way of inserting part-products into a main product. Thereby, different products that are fed as continuous streams are led together along at least one grouping stretch (grouping section), realised by a belt conveyor, into groups. Each group is to have a predefined sequence of products. In order to avoid errors in the deposited product stream due to errors in the feed, it is suggested to buffer the products while still in the feed streams, e.g. by way of suitable intermediate conveyors, before delivery to a grouping stretch. The delivery is not to be effected until an adequate number of products for creating a complete group is present in all buffers. As the case may be, the creation of a group is delayed until this is the case.
This method however only remedies an error source that leads to faulty product units. Basically, however, there are a plurality of reasons as to why a product unit is not composed or only in a faulty manner.
U.S. Pat. No. 5,547,175 describes a method for creating individualised product units from several products, which are aggregated (grouped together) in each case into a stack. The device incudes two printing stations that are controlled by a common control device. Individual products can be provided with personalised messages at a first printing station, and the product unit can be provided with a personal address at a second printing station. However, no solution as to how sequences of product units with faulty product units can be repaired without a production interruption and while retaining the predefined sequence are mentioned in the mentioned publication document.